SOLVED - Adding GPUs reduces each cards' output, overall hashrate stays the same

[Fuzzy]

I have 5 cards (6950) plugged in using PCI-E 1x extenders. When I start mining 1 card I get 330 Mhash,
but when I start a 2nd, each one drops to 165 and Total is still 330
Then I start a 3rd card, and each drops to 110 and total is still 110.

I've checked all the miners and they are all assigned to different GPUs.

Using the latest GUI miner. Out of ideas  

[DeathAndTaxes]

Looks like you aren't using different GPU.

Use a non-miner tool like afterburner of gpu-z.  Check GPU load for each card.  My guess is you will see one card @ 100% load and the rest at 0%.

If you can't figure it out w/ GUI Miner then try cgminer.  You only need one instance and it runs all the GPU together.  No scratch that even if you can figure it out w/ GUIMiner STILL use cgminer.  Since instance to control up to 8 GPU, load, fan speed, temp monitoring, built in fan control, overclocking, work prefetching, early block detection, etc.  Simply blows every other miner away.

[RyNinDaCleM]

+1 to CGminer.;
But, you need to make sure you select the correct openCL device from the drop down menu in guiminer. Each card will have a different device id.
In my case it shows:
[0-0]Cayman
[0-1]Cypress
[0-2]Cypress
[0-3]Cypress

[sadpandatech]

+1 to CGminer.;
But, you need to make sure you select the correct openCL device from the drop down menu in guiminer. Each card will have a different device id.
In my case it shows:
[0-0]Cayman
[0-1]Cypress
[0-2]Cypress
[0-3]Cypress

  This, and make sure you don't have the same 'device=#' in the extra flags for each card.

[Fuzzy]

+1 to CGminer.;
But, you need to make sure you select the correct openCL device from the drop down menu in guiminer. Each card will have a different device id.
In my case it shows:
[0-0]Cayman
[0-1]Cypress
[0-2]Cypress
[0-3]Cypress

I've been mining on 3 machines since July with no issues besides a few dead PSUs. 4, 3 and 2x HD6950s in each machine.

Since learning that you can use 1x PCIE raisers, I ordered 9, shorted the appropriate pins and have 5 cards hooked up to one machine now.

The difference is that they're now on 1x PCIE lanes instead of 16x and 8x, which doesn't matter as 1 card will still pull ~320Mhash when mining by itself.
Also, I have a separate 1250W PSU for the cards, and a 450W for the mobo/drive.
Still running XP 32-bit, but with the new ATI 11.9 drivers and 201108 GUI miner

Each card is visible in the Device Manager, Catalys Control Centre, and in GUI miner, and each miner was pointing to a different card.

I tried again with just two cards plugged straight into the mobos 16x lanes but still have the same problem, overall hash hovers at 300.

I'm gonna try a fresh install with the old 11.5 Cat and GUI miner and ini file.

[finway]

you didn't enable these GPU.   My suggestion: plug on the resistance

[DeathAndTaxes]

Just use cgminer.  It will show you all the card, their individual hashrate, and the % load on each.

[Fuzzy]

The problem has disappeared after re-installing XP SP3 32bit and installing only nForce Lan drivers, Catalyst 11.5 and .net 3.5 Framework.

However, another problem has crept up. Any 4 cards will mine perfectly fine, but adding a fifth card will make "[0-4] Cayman" ALWAYS fail verification, even when it's the only card mining. Disconnecting any other card fixes the problem, but then the highest card on the list is only "[0-3] Cayman".

[finway]

Windows dont support more than four cards.

[DeathAndTaxes]

Windows dont support more than four cards.

Windows supports 8 GPU but I think it requires a newer driver version.  OP Try using latest Catalyst driver.  Maybe someone else can chime in on the exact driver ver but the newer ones support 8 GPU on windows.  All driver versions support 8+ GPU in linux.

[Fuzzy]

Installed Catalyst 11.9 and the split hashrate problem is back.

[DeathAndTaxes]

Have you tried cgminer.  If nothing else it should make it easier to diagnose what is going on.

My guess is that somehow guiminer is sending everything to one card.  I have noticed with AMD drivers that changing in and out lots of cards and changing slots can sometimes cause "issues" where the drivers get confused.  Before anything else I would try cgminer.

[Fuzzy]

CGminer ignores every other card (hash rate stays at 0) with 4 cards, and crashes before even starting with 5   

[sadpandatech]

CGminer ignores every other card (hash rate stays at 0) with 4 cards, and crashes before even starting with 5   

  Something we forgot to ask. You don't have crossfire turned on do you?  Or have some option for it in the mobo that is on?

  If nothing else the limit on yours is probably going to be the lane handling done by your boards ICH chip.  I assume you rolled back to 11.5? Have you tried 11.8?

  Also, what is the model of your mobo and have you tried with x1 extenders?

[DeathAndTaxes]

CGminer ignores every other card (hash rate stays at 0) with 4 cards, and crashes before even starting with 5   

Wow well you got me stumped.

Just to be clear this is with
a) Windows 7 clean install
b) Only 11.9 drivers installed (not jumping around driver versions)

If so then that is beyond bizare.  Might be hardware specific.  I have never seen that and never heard of it happening to someone else.

If this occured on a clean install then I guess your best bet is a clean install w/ 11.5 and 4 cards (which you indicated did work above) or trying linuxcoin.

If you end up having same problems w/ linux coin (which comes w/ 11.5 drivers installed) then it puts even more weight on some weird MB PCIE routing issue.

[conspirosphere.tk]

I use to have a kind of similar problem (card correctly identified by Windowze xp64 and utilities like sapphire trixx but Phoenix crashing on all but the one connected to a monitor). My fix: extend the monitor to all the cardz in screen properties.

[eroxors]

For the record, I'm having this exact problem.

Running a 6970 and 5870 in one box, one on the x16 slot, one on an x1 slot wire modded with an extender. Overall hashrate is around 400 when using both cards, at about 200 each. Afterburner shows that the load is fluxuating between 40/60% between the card, roughly adding up to 100%. GUI miner shows that I'm selecting Cayman for the first miner and Cypress for the second (checked and double checked). I'm using the Feb. version of GuiMiner and XP SP3, Catalyst 11.7, sdk 2.5.

I'll respond here when I figure out what's going on.

[fabrizziop]

Try to install 11.6 first, and uninstall it, and then install 12.1. That fixed a lot of problems for me, and took me some days to figure it out.

[eroxors]

I ended up ditching XP and everything works fine on Win7 32bit. Lame.

[twmz]

I ended up ditching XP and everything works fine on Win7 32bit. Lame.

I agree.  XP is lame.